Sr‐Enriched Glassy Picrites From the Karoo Large Igneous Province are Evolved, not Primitive Magmatic Rocks

Magmatic products of the Karoo Large Igneous Province can be divided into a volumetrically dominant, compositionally uniform low-Ti tholeiitic suite, and subordinate, geographically restricted, diverse, incompatible-rich high-Ti suite. High-Ti picrites contain up to 2,400 ppm Sr, 1,900 Ba, 550 Zr, which seems unusual for olivine-enriched rocks. We studied six determine phase(s) in Sr resides. Samples consist 10–30% olivine phenocrysts groundmass brown glass, augite, feldspar, ilmenite, apatite. Glass compositions vary, but are generally evolved, ranging from basaltic trachyandesite dacite. X-ray intensity maps demonstrate that most resides glasses, lesser extent, feldspars, if present. Some samples two texturally distinct best modeled terms magma hybridization: variably accumulated surrounded by evolved Sr-rich (to 9,470 ppm) Type 2 melts formed extensive fractionation were infiltrated chemically 1 melts. Upon eruption, melt quenched minor glass around phenocrysts, dominant acquired its composition quench crystallization mineral phases. Both glasses rich H2O (up 3.8 wt. %) nearly devoid CO2. Calculated parental have much higher K2O incompatible trace elements (e.g., or Ba >1,200 relative tholeiites. The imply derivation small degrees partial melting SCLM mantle sources enriched other incompatibles.